In an Australian report in TV around 1980 I saw the John Frum Movement flag: five horizontal stripes of red-green-red-green-red, blue square canton with the green star and yellow ring covering three stripes. A customary flag - John Frum's - with allegiance to the Tanna Kingdom.
Jaume Ollé, 10 June 1998 and 30 January 1999

White Sands (Tanna) flag
image
by Thanh-Tâm Lê

Jaume Ollé's flag [vu}jfrum.gif] looks like the flag used today on the island by the villagers of White Sands, but instead of the "tanna" star in the canton, there are 5 black stars on a brown background arranged in saltire, the one in the middle being greater than the others.
Pascal Monney, 14 June 1998 and 1 February 1999

The Flags of Paradise 1996 chart has a flag of similar striped appearance, but with ca. 3:5 proportion and a large black canton with four 4-pointed "stars" placed in a square pattern. The flag is captioned: John Frum Flag - Gilbert Islands - 1940's.

Who is (was) this John Frum? Tanna and Kiribati are more than 2,000 km apart so I cannot imagine that "John Frum" ruled the two archipelagos. Is (was) he rather a kind of "Oceanian" Marcus Garvey, who would have inspired "liberation movements" throughout the Pacific, his "colours" being used in different areas as flag basis? What do these "4-pointed stars" stand for? They also appear in the flag of the Epi District (Vanuatu). Are they really stars, or wind roses, or something else?
Ivan Sache, 24 July 1999

There has been intensive anthropological research into cargo cults, escapist cults, where the leaders promised their followers that a great bird would carry a world of goods if they followed certain rituals. These cults were in the late 1930's rather isolated. It spread like wildfire when the villagers from a village in Malaita (Solomon Islands), who had fled to the woods, got back to their village to find out the colonial oppressors had left and a huge bird was standing near the village filled with all the goods of the world. It was an American transport plane, which mysteriously had been left by the crew, but the word spread. In Tanna the Americans built a huge town and then the war was over, so they left it to the villagers. It seems that one of the villagers asked an American who they were. The answer, "John from America", which the villagers translated into John Frum. The phenomenon of cargo cults was observed from the Dutch East Indies to French Polynesia, and was alternatively called John Frum movement. A rather universal emblem was the Red Cross, as many goods were from Red Cross relief. Perhaps the star is the symbol of the origin of the bird: the stars, but I'm sure Jaume Ollé will know that!
Jarig Bakker, 24 July 1999

According to Ralph Bartlett (Flag Society of Australia secretary), this flag (No 124 on the Flags of Paradise 1996 chart) was sourced from a (partly hidden) colour photograph in a book called Pacifica Myth, Magic and Traditional Wisdom from the South Sea Islands, Angus & Robertson 1993, page 107. John Frum lived on the island of Tanna during World War Two. Ralph accidentally labeled the flag as coming from the Gilbert Islands (nowadays Kiribati) on the chart.
Nozomi Kariyasu, 28 August 1999

On BBC2 in 'Around the World in 80 Faiths' the John Frum cult is shown where
the adherents of John Frum have incorporated the raising of several US flags
every morning and their lowering each evening into their rituals; they have
actually become sacraments, and every adherent is expected to make his or her
way to a particular spot where four flagpoles are positioned. The flags include
a contemporary S&S, the far right is the contemporary US Marine Corps Standard,
while to the immediate right of the S&S was what appeared to be an olive green
flag; the wind had not caught this flag, and I could not make out any details.
To the left of the S&S was what appeared to be either the Texas or the North
Carolina flag.Ron Lahav, 3 January 2009

I'm certain that the
"fourth flag" is the modern flag of Vanuatu, with red on top and green below.
No other flag in that area uses such colors, therefore I'm sure that it is
the flag of Vanuatu.Michal W., 6 July 2011

The most likely candidate for blue flag with charge in yellow ring would be a
Tanna flag. Would seem to make sense, for the John
Frum movement.Peter Hans van den Muijzenberg, 6 July 2011

There is also a depiction of an
American flag as well as a modern (modern by 1991 standards at least) flag of
the movement. The 1991 flag a single white star on a blue background at the
right, with the same type of red and green stripes seen on other John Frum
flags featured above. Michal W., 6 July 2011